There are already several cursor-control devices integrating functions of the computer mouse and the presentation device. However, the control methods adopted thereby are still similar to those conventional computer mice and thus suffering the same limitations. As for the inertial/gravity mouse which are being aggressively studied, it is still troubled by many technical difficulties and thus remains to be improved.
There are many researches relating to inertial mouse. One of which is an input device disclosed in U.S. Pat. No. 5,898,421, entitled “Gyroscopic Pointer and Method”, as seen in FIG. 1. The hand-held input device, having an inertial gyroscope 110 arranged therein, is capable of being used in free space, employing the inertial gyroscope 110 for detecting angular velocity of a user's hand and thus, by the signal transmission of the interface 180, defining movements of a cursor displayed on a screen of an interactive computer. In one embodiment of the aforesaid patent as that shown in FIG. 1, the inertial gyroscope 110, arranged inside the hand-held input device, is driven to rotate by power provided from a wall adapter 190 and is pivotally coupled to an inner frame 170 by a pair of coaxial gimbals 115, 120 while pivotally coupling to an outer frame 160 by another pair of coaxial gimbals 140, 145 whose axis is perpendicular to that of the gimbals 115, 120. As there is only a gyroscope 110 configured in the hand-held input device, it is only suitable to be used in a free space and is not able to operate on a planar surface. Moreover, it is conceivable that the referring mouse is comparably bulky and suffers a high margin of error as gyroscope 110 is mechanically coupled inside the hand-held input device.
Please refer to FIG. 2, which shows a pointing device disclosed in U.S. Pat. No. 5,825,350, entitled “Electronic Pointing Apparatus and Method”. The foregoing pointing apparatus 100 is capable of controlling cursor movement and selecting elements on a computer screen no matter it is being held to move on a planar surface or in a free space, in which two gyroscopes, respectively coupled to a gyroscope printed circuit board 452, are provided for indicating yaw and pitch movements of the pointing apparatus in free space, and a mouse ball 260 and relating mouse ball encoders are provided for indicating movement of the pointing device on a planar surface. The switching of the pointing apparatus 100 between a two-dimensional mode and a three-dimensional mode is enabled by a ball locking mechanism, which is comprised of a lever 472 and a plunger 270, connected to the lever 472. That is, when the pointing apparatus 100 is being held to move on a planar surface, the plunger 270 that extends out of an opening of the housing is pushed through the opening to a position substantially level with the surface of the bottom side and thus lifts the lever 472 for freeing the mouse ball 260, so that the pointing apparatus 100 is being enabled to operate in the two-dimensional mode, and when the pointing apparatus 100 is being lift and move in a free space, the plunger 270 will drop and thus pull the lever 472 to press down while enabling the elevated region 506 to press upon the mouse ball 260 for holding the same from rolling freely, so that the pointing apparatus 100 is being enabled to operate in the three-dimensional mode. Although the aforesaid pointing apparatus is operable no matter it is being held to move on a planar surface or in a free space, it is still not preferred, since when the pointing apparatus 100 is being lift and move in a free space, it is more than likely that the cooperative effort of the lever 472 and its elevated region 506 can not precisely hold the mouse ball 260 still that the mouse ball 260 is intended to roll or move unexpected and causes the pointing apparatus 100 to generate unwanted signals interfering the cursor movement on the screen.
There are some consumer products, similar to the pointing apparatus shown in FIG. 2, currently available on the market that each can be considered as a standard LED optical mouse with addition gyroscope arranged therein and is different from that of FIG. 2 by replacing the mouse ball 260 with an optical module and thus the problem caused by the unexpected rolling of the mouse ball is prevented. However, such optical gyroscope mouse is just a housing accommodating two separated and independent modules, one acting as a common LED optical mouse while sitting on a planar surface, and another acting as gyroscope to detect the angular velocity of rotation while operating in free space, that the circuit of the LED optical module has no relation with the gyroscopic circuit. Therefore, not only such optical gyroscope mouse can not benefit from the design since it can only provide basic functions the same as the addition of a standard LED optical mouse and a gyroscope, but also it is a heavy, bulky and complicated device.
Please refer to FIG. 3, which is gravity mouse disclosed in TW Pat. Appl. No. 90221010. As the gravity mouse is being held to move and used for controlling the movement of a cursor displayed on a monitor of a personal computer (PC), its gravity sensor (i.e. G sensor) with potential energy measuring ability is enable to detect the potential energy variation of the gravity mouse caused by a movement of the same while transmitting a signal generated accordingly to its micro process unit (MCU) to be processed. As the MCU is able to detect the duration of the movement while receiving an acceleration caused by the movement, it can generate a control signal for controlling the cursor to move accordingly with respect to the duration and the acceleration. It is known that the movement of the cursor is determined by a integration operation performed based upon the detections of at least two accelerometers configuring in the gravity mouse at two perpendicular axes. Thus, as the movement is defined by integration which is prone to accumulate error, the positioning of the cursor might not be accurate.
Therefore, it is in need of an inertial sensing input apparatus that is accurate and convenience to operate no matter it is being held to move on a surface or in a free space, by which not only the unconscious rotation caused by a human operation as it is being held in a human hand is compensated, but also the interferences caused by the electronic noises generated from the accelerometer can be prevented for freeing the inertial sensing input apparatus of the invention from the shortcomings of prior-art inertial input apparatus using only accelerometers.